//support.js 函子
class Container {
    constructor(value) {
        this._value = value
    }
    static of(value) {
        return new Container(value)
    }
    map(fn) {
        return Container.of(fn(this._value))
    }
}

class Maybe {
    constructor(x) {
        this._value = x
    }
    static of(x) {
        return new Maybe(x)
    }
    isNothing() {
        return this._value === null || this._value === undefined
    }
    map(fn) {
        return this.isNothing()? this : Maybe.of(fn(this._value))
    }
}
module.exports = { Maybe, Container }